x
ILLUSTRATIONS
| Fig. | 3. | Diagrammatic reconstruction of imagined Dipleurula ancestor | 43 |
| 4. | Diagrammatic reconstruction of imagined primitive Holothurian type | 44 | |
| 5. | Eldonia ludwigi, new species | 47 | |
| 6. | Synaptula hyrdriformis (Lesseur) | 54 | |
| Figs. 7, 7a. Levisia nasuta, new species | 87 | ||
| 8. | Emeraldella brocki, new species | 204 | |
| 9. | Emeraldella micrura, new species | 205 | |
| 10. | Sidneyia inexpectans Walcott | 206 | |
| 11. | Near view of Tah Peak, Robson Peak District | 330 | |
| 12. | Robson Peak from northwest slope of Mahto Mountain | 331 | |
| 13-16. Saukia coloradoensis, new species | 376 | ||
| 17. | Saukia junia, new species | 378 | |
| 18-20. Saukia rustica, new species | 383 | ||
